steve and scott paper

http://content.nejm.org/cgi/content/extract/337/11/762

http://www.pnas.org/content/86/8/2757.abstract

http://www.pnas.org/content/105/33/11595.full

Sickle Cell Anemia is a genetically inherited disease that affects the formation of red blood cells. This deformity affects how the blood cells move through the circulatory system. This defect can have some devastating affects to organs or cause infections. Sickle Cell is autosomal recessive so only a person with two defective genes contract the disease. Individuals with sickle cell anemia didn’t live very long until more recently. However, being a carrier of the disease offered a genetic advantage in the areas that malaria was a danger.
The Sickle mutation is believed to have a multicentric origin believed to be started in Asia and Western Africa with migrations thought Africa area (A.E. Kulozik 241). There has been evidence that there were several natural mutations throughout Africa (A.E Kulozik 242). This is interesting, because it would seem a biological pressure was there to select for this mutation. Another study indicates that it arouse separately in three different locations in Africa based on three distinct different halotypes being found in 3 different regions of Africa (J Pagnier 1771). Sickle cell was moved throughout Africa and eventually throughout the Europe and the Americas through the slave trade. This pretty much guaranteed a world wide spread of Sickle Cell anemia.
Sickle Cell Anemia is a genetically inherited disease. It is an autosomal recessive inherited, which means it requires two mutated genes for a person to contract the disease. If a person receives only one mutated gene they are said to be a carrier for the disease. Very rarely does a person with only one gene contract the disease but it is possible. The only way to get this disease is for one to inherit it, a mutation after birth won’t happen.
The genes involved in sickle cell anemia control the protein production in red blood cells called hemoglobin. The basic function of Hemoglobin is to bind oxygen and deliver it to tissues in the body. The disease manifests itself by having rigid, abornmal, sickle shape and reduces cells flexibility that results in various complications. This disease is most prevalent in regions that are known to have malaria.

References
E. Kulozik, J. S. Wainscoat, G. R. Serjeant and others. Geographical survey of βS-globin gene haplotypes: Evidence for an independent Asian origin of the sickle-cell mutation. American Journal Human Genetics Volume 39 239-244. 1986.
J Pagnier, J G Mears, O Dunda-Belkhodja and others. Evidence for the multicentric origin of the sickle cell hemoglobin gene in Africa. Proceedings of the National Academy of Sciences of the United States of America. Volume 81 1771-1773. 1984.

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